Advances in electronic devices including microprocessors have created a large market for compact electronic apparatus using memory or PC cards, hard disk drives (HDDs), etc. A docking connector or a memory card connector is used in such electronic apparati. The docking connector is used to interconnect another similar electronic apparatus for creating a network and also to connect peripheral equipment such as a submemory apparatus. A memory card connector receives one or more memory card or an HDD for electrical connection thereto.
Recently, needs have arisen for card type devices known a PC cards for expansion or additional performance of compact electronic equipment such as notebook personal computers. Such PC cards are normally received in a PC card connector installed in a compact electronic equipment to provide added memory capacity or interfacing with external devices such as peripheral equipment. Typically, PC card connectors have dual stacked connector mating portions to permit reception of three types of PC cards, i.e., Type I, Type II and Type III.
These docking connectors and PC or memory card connectors include a plurality of contacts often more than one hundred disposed in a matrix having a plurality of rows. Such contacts are bent at right angles or in an L-shape with respect to the connector and are soldered to respective conductive paths or traces on a main PC board. One example of such memory card connector is disclosed in U.S. Pat. No. 5,324,204. In this particular example, four rows of contacts are bent in a staggered relationship to be connected to the main PC board in eight rows.
Typical examples of such connectors also are disclosed in Japanese Patent Publication, No. 6-332573 and Japanese UM Publication No. 6-56992. The former connector has contacts aligned in a connector housing and bent at substantially right angles at the rear position to be connected to a rain circuit board. In the latter connector, contacts of dual stacked connectors extend at their rear positions toward each other, i.e., toward the center position to be connected to an auxiliary circuit board at the center position, thereby interconnecting the auxiliary and main circuit boards by the board-to-board connector.
Unfortunately, as electronic equipment becomes more compact, a higher density of contacts is required. The individual contacts, therefore, have smaller dimensions and pitch, which makes it difficult to form reliable connections with a main circuit board using a connector having relatively long solder tines of the contacts of the former connector. Although the latter connector is effective to realize relatively fine pitch connections, the connector requires a larger number of components, thus making it more difficult to manufacture and more expensive.
Moreover, a standard to form signal and ground (SG) of PC card connectors has been added recently. One object is to isolate signals to be transmitted through one connector from those transmitted through another connector, thereby preventing noise due to cross talk. Unfortunately, however, such noise protection is not always sufficient in conventional connectors.
Additionally, in the above conventional connectors, the connection or mounting location of the connector or its contacts on a main circuit board is required to be predetermined, thereby restricting the design of the main circuit board and precise manufacture of conductive through hole patterns, etc. with small tolerances. It is, therefore, desirable to provide flexibility in connection or mounting.
Using a flexible circuit (FC) for interconnecting circuits on a substrate such as a small-size printed circuit board (PCB) and high-density-mounted electronic equipment is known in the art. Such an electrical connector for an FC generally comprises a plurality of contacts to be engaged with conductive pads formed on the FC, a housing for disposing and holding the contacts, and a movable plastic cover or other member for pushing the FC into the housing and the conductive pads formed thereon into positive engagement with the contacts in the housing. Examples of conventional electrical connectors for FC are disclosed in a Japanese Patent Publication No. 61-131382, a Japanese UM Publication No. 2-120780, and a Japanese Patent Publication No. 5-251140.
U.S. Pat. No. 3,923,364 discloses an electrical connector assembly including a housing having a plurality of contacts disposed along an elongate opening; a shielded flexible substrate having a width corresponding to the opening of the housing and conductive signal traces and pads and ground conductive pads on one surface thereof corresponding to the contacts in the housing; and a guide member having a plate portion to be disposed in a flexible substrate bent in a generally U-shape with the one surface outside to be inserted into the opening of the housing whereby, upon inserting the guide member and substrate into the housing opening, the signal and ground pads on the one surface of the substrate are electrically engaged to corresponding contacts in the housing.
As electronic equipment becomes smaller with a higher density of contacts, e.g., the pitch of the contacts is less than 0.5 mm, the dimensions of the contacts to be used therein will also become smaller and, therefore, be more easy to deform. It is very difficult to accurately position the contacts, especially their solder-terminating portions, in the desired location and to maintain them so as not to deform the contacts upon handing and mounting the connector on to the substrate.
Also, for the electrical connector utilizing the FC, it is difficult to precisely and firmly urge the movable plastic cover to engage over the full width of the FC with the plurality of contacts without having some deformation over the full width of the FC. Accordingly, reliability of connection between the conductive pads and the contacts has been decreased.
Therefore, an object of this invention is to provide a small and high density electrical connector assembly, that utilizes the FC and enables simple structure and easy handling.
It is another object of this invention to provide an electrical connector assembly having a ground function and permitting easy handling in which the plurality of the conductive pads on the FC and the contacts in the housing are interconnected with high reliability.
It is yet another object of this invention to provide an electrical connector assembly for card bus, which enables one or more memory card connector etc. to connect easily and reliably to the PC board.
In order to solve the problems of the prior art electrical connector assembly and to achieve the above mentioned objects, the electrical connector assembly of the present invention comprises a housing having plural rows of contacts, a substrate, such as a flexible printed circuit board (FC) to be connected to the contacts of the housing at both ends of the flexible printed circuit board, said printed circuit board having a plurality of conductive traces and pads, and a guide member to be inserted in the FC, the guide member being bent in a generally U-shape to force the FC between rows of contacts of a corresponding connector to interconnect the conductive traces and contacts.
In accordance with one aspect of the present invention, the electrical connector assembly includes a housing having a plurality of contacts disposed along an elongate opening; a flexible substrate having a width corresponding to the opening of the housing and conductive traces on one surface thereof corresponding to the contacts in the housing; and a guide member having a plate portion to be disposed in a flexible substrate bent in a generally U-shape with the one surface outside to be inserted into the opening of the housing. The connector assembly is characterized in that: the housing includes a ground conductive member at at least one end thereof; the flexible substrate is formed with a ground conductor on the other surface thereof; and the guide member is a conductive member adapted to further provide a connection to ground for the assembly whereby the contacts and the conductive traces are electrically connected by the force exerted by the guide member on the flexible substrate and the ground conductor of the substrate is connected to the ground conductive member of the housing by the guide member.
In one embodiment of the invention using a flexible substrate having conductive traces on one surface, the assembly further includes strengthening plates disposed on the other surface of the substrate at the locations corresponding to the conductive pads.
One aspect of the present invention is an FC having two arrays of corresponding conductive pads and conductive traces on one surface with the plurality of conductive pads of the arrays arranged in rows in an opposed relationship. A plurality of openings are disposed between the arrays leaving narrow bridge portions between adjacent openings. Strengthening plates are attached to the reversed surface at the positions corresponding to the conductive pads with portions of the strengthening plates extending into the openings by a predetermined length.
Also, another aspect of the present invention is a flexible circuit (FC) comprising conductive traces on one surface of a central film, a ground layer on the reverse surface, and cover layers disposed to cover the conductive traces and the ground layer. A plurality of openings are formed in the cover layers substantially in rows at selected locations that avoid the conductive traces.
The FC according to the present invention has openings in the direction of the width at substantially center position between the rows of the conductive pads. The openings define the relatively narrow bridge portions of the FC. The FC has a pair of strengthening plates adhered to both sides of the openings and at least one surface of the FC. The pair of strengthening plates have edges extending into the openings by a desired length from both sides thereof.
Additionally, the FC according to the present invention has a plurality of recesses arranged substantially in rows near the bent portion. The recesses are preferably formed by removing a part of one layer of a multiple-layer FC, thereby allowing the FC to bend smoothly at a desired position.
The FC is bent or folded along the bridge portions before being inserted into a connector along with a guide member, and upon full insertion of the board and guide member, the conductive pads of the FC are electrically connected with contacts in the connector. The edge portions of the strengthening plates then abut the bottom in the housing for proper positioning of the FC in the connector, thereby assuring reliable electrical connection between the conductive pads and the contacts. Also, it is bent at a desired angle, preferably a right angle along the recesses, thereby permitting connection to a connector such as the PC card connector or other device at the edge portion. Since the electrical connector assembly comprises a FC with no individual contacts bent at right angle with respect to a wall or L-shape as seen in the prior art electrical connector assembly, the connector of the present invention eliminates deformation of the guide between the contacts and disengagement and short circuit caused therebetween. Accordingly, stable electrical connections and easy handling are achieved. Also, the structure having the FC connected to the contacts on the housing at the both ends thereof enables high density.
According to another aspect of the present invention, the electrical connector comprises a housing having two rows of contacts alone an elongate opening, a flexible printed circuit board having a plurality of conductive traces on a surface corresponding to these contacts, and a guide member having a generally planer portion to be inserted into a U-shaped bent portion of the flexible printed circuit board, wherein the conductive traces on the flexible printed circuit board are forced between the rows of the contacts by means of the guide member for establishing electrical interconnection between the conductive traces and the contacts in the housing, thus electrically connecting the contacts with corresponding contacts of at least one electrical connector terminated to the ends of the FC.
According to the electrical connector assembly, it is possible to connect the high frequency signals to the contacts through the conductive traces on the surface of the FC. The FC is bent in a U-shape to envelope the guide such that the guide electrically engages the ground conductor of the FC board and upon inserting the FC into the housing, the guide electrically engages the ground conductive members of the housing. Since all the conductive traces formed on the one surface of the FC can be signal traces, a high density and high frequency electrical connector is obtained.